PBP Element Corrects Chromatic Aberration in Pancake Lenses
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Solution Overview
Problem
Optical devices for virtual, augmented, and mixed reality applications face challenges in achieving compactness, lightweight design while maintaining high resolution and low chromatic aberration, particularly with pancake lenses that suffer from strong chromatic aberration due to their focal nature and multiple reflectors, leading to reduced image quality.
Innovation Solution
Incorporating a Pancharatnam Berry Phase (PBP) element with an opposite Abbe number to the optical lens, which corrects chromatic aberration by manipulating the optic axes of liquid crystals, thereby simplifying the lens design and reducing fabrication costs and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a pancake lens with multiple reflectors is used to achieve compact form factor, then the device size is reduced, but chromatic aberration increases significantly
Solution Approach 1:
The optical system is segmented into multiple functional elements: the pancake lens assembly and the separate achromatic doublet. This segmentation allows each component to address specific optical requirements - the pancake lens provides compactness while the achromatic doublet corrects chromatic aberration, resolving the contradiction between small form factor and low chromatic aberration.
Solution Approach 2:
The achromatic doublet uses composite lens construction with at least two lens elements made of different materials having different Abbe numbers. This composite structure enables chromatic aberration correction by combining materials with complementary dispersion properties, allowing the system to maintain compact form factor while reducing chromatic aberration.
2Object-affected harmful factors
If conventional achromatic doublets are used to correct chromatic aberration, then chromatic aberration is reduced, but manufacturing cost and complexity increase
Solution Approach 1:
The patent introduces the achromatic doublet as an intermediary optical element positioned between the display element and the pancake lens. This intermediary component specifically addresses chromatic aberration without requiring modification to the existing pancake lens manufacturing process, thereby reducing chromatic aberration while minimizing increases in manufacturing complexity.
Solution Approach 2:
The achromatic doublet utilizes parameter changes in material properties, specifically selecting lens materials with different Abbe numbers to achieve chromatic aberration correction. By changing the material parameters rather than the structural complexity, the system achieves better optical performance with relatively simple manufacturing approaches.
3Measurement precision
If multiple optical elements are used to achieve high resolution, then image quality improves, but device weight increases
Solution Approach 1:
The achromatic doublet employs thin-film optical elements and streamlined lens designs that provide the necessary optical functionality for high resolution while minimizing material usage and overall weight. This allows multiple optical elements to be integrated without proportionally increasing device weight.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The PBP element effectively corrects chromatic aberration in pancake lenses, enabling a compact, lightweight optical system with improved image quality and reduced form factor, addressing the limitations of conventional achromatic doublets in terms of cost and aperture size.
Implementation Method 1
a Pancharatnam Berry Phase (PBP) element coupled to the optical lens. The PBP element is configured to provide chromatic aberration correction for the optical lens
Implementation Method 2
which corrects chromatic aberration by manipulating the optic axes of liquid crystals
Implementation Method 3
a quarter-wave plate optically coupled to the linear polarizer
Implementation Method 4
a linear polarizer disposed at a surface of the second optical element
Implementation Method 5
a lens system typically includes multiple optical elements, such as one or more of a lens, a waveplate, a reflector, etc., for focusing the image light to the eyes
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
An optical lens assembly includes an optical lens and a Pancharatnam Berry Phase ("PBP") element coupled to the optical lens. The PBP element is configured to provide chromatic aberration correction for the optical lens. An Abbe number of the PBP element and an Abbe number of the optical lens have opposite signs.